Runtime error on binstir

[mrphilb]

i ran my code for binary stirling numbers on ideone just fine, no errors except tle for large numbers, but here i'm getting runtime error, not sure why. here's my code

def stirling(n,m):
    if n<m:
        return 0
    elif m == 0 and n == 0:
        return 1
    elif m == 0:
        return 0
    else:
        return (m&stirling(n-1,m))^stirling(n-1,m-1)
cases = int(input())
while cases >0:
    a,b = input().split()
    print(stirling(int(a),int(b)))
    cases -= 1

[numerix]

I can't tell you a testcase where your code fails, but according to my experiments with your code it seems a problem of exceeding the maximum recursion depth. You should try an approach without recursion.